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Entropy versus enthalpy in hexagonal-close-packed highentropy alloys

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Rare Metals 2022年第8期41卷 2906-2920页

作者： Xin-wei yang Xiao-Hui Shi Hui-Jun yang Jun-wei Qiao Peter KLiaw Yu-Cheng Wu College of Materials Science and Engineering Taiyuan University of TechnologyTaiyuan030024China School of Materials Science and Engineering University of TennesseeKnoxville37996USA School of Materials Science and Engineering Hefei University of TechnologyHefei230000China

The addition of hexagonal-close-packed(hcp)non-rare-earth elements Zr,Ti and Co,to the 10-component hep rare-earth-based high-entropy alloys(HEAs)with a composition of ScYLaNdGdTbDyHoErLuX(X=Zr,Co and Ti)was *** enthalpy of mixing between elements was found to have a significant effect on the formation of *** addition of Co combines with elements that had a strong chemical affinity to form intermetallic compounds by the effect of *** was added with all elements with poor chemical affinity and exhibited rejection to form a phase *** were the two terminal manifestations of the role of enthalpy over *** of Zr was soluble in the matrix under the action of entropy,while the other part had a greater affinity for Sc than the other elements to form a precipitate under the action of *** was the result of the local balance between the effect of enthalpy and *** solid solution of the elements had different degrees of strengthening effect,among which Zr had the most excellent strengthening effect from 185 to 355 MPa,so the solid solution strengthening model and precipitation strengthening model were proposed to predict the strength of the alloy with the addition of Zr effectively.

关键词： High-entropy alloys Hexagonal close-packed(hcp) Phase formation rule Configuration entropy Mechanical properties

A stimuli-responsive pillar[5]arene-based hybrid material with enhanced tunable multicolor luminescence and ion-sensing ability

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National Science Review 2021年第6期8卷 60-69页

作者： Xin-Yue Lou Nan Song Ying-wei yang State Key Laboratory of Inorganic Synthesis and Preparative Chemistry International Joint Research Laboratory of Nano-Micro Architecture Chemistry (NMAC)College of ChemistryJilin University

Tunable luminescent materials are becoming more and more important owing to their broad application potential in various fields. Here we construct a pillar[5]arene-based hybrid material with stimuli-responsive luminescent properties and ion-sensing abilities from a pyridine-modified conjugated pillar[5]arene and a planar chromophore oligo(phenylenevinylene) upon coordination of Cd(II) metal cores. This new material not only shows an optimized luminescence due to the minimized π–π stacking and efficient charge transfer properties benefitting from the existence of pillar[5]arene rings, but also exhibits tunable multicolor emission induced by different external stimuli including solvent, ions and acid, indicating great application potential as a fluorescent sensory material, especially for Fe3+. With this pillar[5]arene-based dual-ligand hybrid material, valid optimization and regulation on the fluorescence of the original chromophore have been achieved, which demonstrates a plausible strategy for the design of tunable solid-state luminescent materials and also a prototypical model for the effective regulation of fluorescent properties of planarπ systems using synthetic macrocycle-based building blocks.

关键词： aggregation-induced emission supramolecular chemistry luminescent materials pillararenes macrocycles

Functional hydrogel coatings

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National Science Review 2021年第2期8卷 151-169页

作者： Junjie Liu Shaoxing Qu Zhigang Suo wei yang Center for X-Mechanics Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province and Department of Engineering MechanicsZhejiang University State Key Laboratory of Fluid Power and Mechatronic System Zhejiang University Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and EngineeringSouthwest Jiaotong University John A.Paulson School of Engineering and Applied Sciences Kavli Institute for Bionano Science and TechnologyHarvard University

Hydrogels—natural or synthetic polymer networks that swell in water—can be made mechanically,chemically and electrically compatible with living tissues. There has been intense research and development of hydrogels for medical applications since the invention of hydrogel contact lenses in 1960. More recently,functional hydrogel coatings with controlled thickness and tough adhesion have been achieved on various substrates. Hydrogel-coated substrates combine the advantages of hydrogels, such as lubricity,biocompatibility and anti-biofouling properties, with the advantages of substrates, such as stiffness,toughness and strength. In this review, we focus on three aspects of functional hydrogel coatings:(i) applications and functions enabled by hydrogel coatings,(ii) methods of coating various substrates with different functional hydrogels with tough adhesion, and(iii) tests to evaluate the adhesion between functional hydrogel coatings and substrates. Conclusions and outlook are given at the end of this review.

关键词： hydrogel coatings coating methods coating tests adhesion hydrogel applications

Conceptual design and preliminary experiment of icing risk management and protection system

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Chinese Journal of Aeronautics 2022年第6期35卷 101-115页

作者： Qiang WU Haojun XU Binbin PEI yang wei School of Aeronautics Engineering Air Force Engineering UniversityXi’an 710038China

Icing is one of the main external environmental factors that causes aircraft to lose *** flight safety assurance system under icing condition is particularly ***,most of the systems do not consider the coupling characteristics of aerodynamics and flight dynamics of icing *** will affect the accuracy of the calculation ***,the icing risk management system helps the pilot to realize the possible dangers in advance and perform correct maneuvers,based on quantitative assessment and visualization methods of flight *** envelope protection system realizes flight safety guarantee based on the real-time boundary protection method of key flight ***,based on distributed simulation technology,a flight simulator was used as a platform to integrate the icing risk management system and envelope protection system to realize man-in-the-loop *** fictional but historically motivated icing scenarios are designed to test the system,and the results demonstrate that the icing risk management and protection system would be useful for aviation safety and can also be used for pilot training and reproducing flight accidents to find the causes.

关键词： Flight risk Flight simulator Icing Quantitative assessment Visualization

Exploring associations between streetscape factors and crime behaviors using Google Street View images

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Frontiers of Computer Science 2022年第4期16卷 45-58页

作者： Mingyu Deng wei yang Chao Chen Chenxi Liu School of Computer Science Chongqing UniversityChongqing400044China School of Management Science and Real Estate Chongqing UniversityChongqing400044China State Key Laboratory of Mechanical Transmission Chongqing UniversityChongqing400044China

Understanding the influencing mechanism of the urban streetscape on crime is fairly important to crime prevention and urban ***,the development of deep learning technology and big data of street view images,makes it possible to quantitatively explore the relationship between streetscape and *** study computed eight streetscape indexes of the street built environment using Google Street View images ***,the association between the eight indexes and recorded crime events was revealed with a poisson regression model and a geographically weighted poisson regression *** experiment was conducted in downtown and uptown Manhattan,New *** regression results show that the influences of Motorization Index on crimes are significant and positive,while the effects of the Light View Index and Green View Index on crimes depend heavily on the socioeconomic *** a local perspective,the Pedestrian Space Index,Green View Index,Light View Index and Motorization Index have a significant spatial influence on crimes,while the same visual streetscape factors have different effects on different streets due to the combination differences of socioeconomic,cultural and streetscape *** key streetscape elements of a given street that affect a specific criminal activity can be identified according to the strength of the *** results provide both theoretical and practical implications for crime theories and crime prevention efforts.

关键词： crime Google Street View streetscape spatial analysis geographically weighted poisson regression

High-fidelity numerical simulation of unsteady cavitating flow around a hydrofoil

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Journal of Hydrodynamics 2023年第1期35卷 1-16页

作者： Nan Xie Yu-meng Tang yang-wei Liu School of Energy and Power Engineering Beihang UniversityBeijing100191China National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics Beihang UniversityBeijing100191China

Cavitation is a widespread and detrimental phenomenon in hydraulic machinery, therefore, it requires to be accurately predicted. In this study, large eddy simulation (LES), scale-adaptive simulation (SAS) and grid-adaptive simulation (GAS) are employed to investigate the unsteady cavitating flow around a NACA0009 hydrofoil. The prediction accuracy of GAS, SAS, both using the shear-stress transport (SST) k — ω model as baseline turbulence model, is validated by comparing with experimental and LES results. The cavity behaviors and turbulence fields are analyzed systematically. Results show that the GAS gives a more reasonable turbulent viscosity and accurately predicts the periodic evolution of typical vortical structures of cavitating flow, such as tip leakage vortex cavitation, tip separation vortex cavitation, leading-edge cavitation, and trailing-edge vortex. The time-averaged cavity volume, volume fluctuation amplitude, and characteristic frequencies of cavities predicted by the GAS are very closed to the LES, while the SAS fails to accurately capture these cavity characteristics. Furthermore, the local trace criterion is applied to extract the vortical structures and to analyze the swirling patterns of the tip leakage vortex. Multi-scale vortical structures in LES are well identified by local trace criterion. The prediction accuracy of the SAS method for small-scale vortical structures, such as the vortex shedding on the suction side and the vortex rope around the tip leakage vortex, is obviously insufficient, while the GAS has a higher accuracy in predicting vortex shedding. The tip leakage vortex and induced vortex extracted from GAS are also closer to that of LES in both swirling patterns and scale.

关键词： Tip leakage vortex cavitation leading-edge cavitation large eddy simulation(LES) grid-adaptive simulation scale-adaptive simulation

Advanced high-order nonlinear chirp scaling algorithm for high-resolution wide-swath spaceborne SAR

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Chinese Journal of Aeronautics 2021年第2期34卷 563-575页

作者： Zhirong MEN Pengbo WANG Jie CHEN Chunsheng LI wei LIU wei yang School of Electronic and Information Engineering Beihang UniversityBejing 100083China Electronic and Electronic Engineering Department Univrsity of ShefeldSheffield S13JDUK

Spaceborne Synthetic Aperture Radar(SAR) is a well-established and powerful imaging technology that can provide high-resolution images of the Earth’s surface on a global scale. For future SAR systems, one of the key capabilities is to acquire images with both high-resolution and wide-swath. In parallel to the evolution of SAR sensors, more precise range models, and effective imaging algorithms are required. Due to the significant azimuth-variance of the echo signal in High-Resolution Wide-Swath(HRWS) SAR, two challenges have been faced in conventional imaging algorithms. The first challenge is constructing a precise range model of the whole scene and the second one is to develop an effective imaging algorithm since existing ones fail to process highresolution and wide azimuth swath SAR data effectively. In this paper, an Advanced High-order Nonlinear Chirp Scaling(A-HNLCS) algorithm for HRWS SAR is proposed. First, a novel Second-Order Equivalent Squint Range Model(SOESRM) is developed to describe the range history of the whole scene, by introducing a quadratic curve to fit the deviation of the azimuth FM rate. Second, a corresponding algorithm is derived, where the azimuth-variance of the echo signal is solved by azimuth equalizing processing and accurate focusing is achieved through a high-order nonlinear chirp scaling algorithm. As a result, the whole scene can be accurately focused through one single imaging processing. Simulations are provided to validate the proposed range model and imaging algorithm.

关键词： High-Resolution WideSwath(HRWS) Imaging method Second-Order Equivalent Squint Range Model(SOESRM) Signal processing Synthetic Aperture Radar(SAR)

Application of Hilbert-Huang Transform to the Analysis of the Landslides Triggered by the Wenchuan Earthquake

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Journal of Mountain Science 2015年第3期12卷 711-720页

作者： yang Chang-wei ZHANG Jian-jing BI Jun-wei School of Civil Engineering Key of Transportation Tunnel EngineeringMinistry of EducationSouthwest Jiaotong University State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of Technology

A steep rock hill with two side slopes located at DK30＋256 of National Road 213 was used as a prototype for analysis. The full process from initial deformation to sliding of the slope during ground shaking was simulated by using a new Continuum-based Discrete Element Method. During the earthquake, when shaking amplitudes were lower, the stress concentration points firstly appeared at the top of the slip mass, and then some tension failure points appeared, followed by shear failure points. At the same time, both the instantaneous frequencies of accelerations in the bedrock and that in the slip mass basically stayed in two different ranges. The energy transmittance coefficients of the sliding surface also stayed in a high range. As the ground shaking lasted, the number of failure points gradually increased until landslide occurrence. The instantaneous frequencies of accelerations in the slip mass and the energy transmittance coefficients of sliding surface gradually decreased, and both finally converged to a lower range. And then, the reasons triggering landslides are analysis in the joint time-frequency domain using Hilbert-Huang Transform, as follows： the differenees of distribution and dissipation of the earthquake energy and the inconsistency of movements between the slip mass and the bedrock were the two major influence factors.

关键词： Discrete Element Method Hilbert-Huang Transform Wenchuan Earthquake Landslide

Analysis of the rogue waves in the blood based on the high-order NLS equations with variable coefficients

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Chinese Physics B 2021年第11期30卷 151-169页

作者： Ying yang Yu-Xiao Gao Hong-wei yang College of Mathematics and Systems Science Shandong University of Science and TechnologyQingdao 266590China Qingdao West Coast New Area Hospital of Traditional Chinese Medicine Qingdao 266590China

The research of rogue waves is an advanced field which has important practical and theoretical significances in mathematics,physics,biological fluid mechanics,oceanography,*** the reductive perturbation theory and long wave approximation,the equations governing the movement of blood vessel walls and the flow of blood are transformed into high-order nonlinear Schrodinger(NLS)equations with variable *** third-order nonlinear Schrodinger equation is degenerated into a completely integrable Sasa–Satsuma equation(SSE)whose solutions can be used to approximately simulate the real rogue waves in the *** the first time,we discuss the conditions for generating rogue waves in the blood vessels and effects of some physiological parameters on the rogue *** on the traveling wave solutions of the fourth-order nonlinear Schrodinger equation,we analyze the effects of the higher order terms and the initial deformations of the blood vessel on the wave propagation and the displacement of the tube *** results reveal that the amplitude of the rogue waves are proportional to the initial stretching ratio of the *** high-order nonlinear and dispersion terms lead to the distortion of the wave,while the initial deformation of the tube wall will influence the wave amplitude and wave steepness.

关键词： rogue wave variable-coefficients high-order nonlinear Schrodinger equation deformable blood vessels Sasa-Satsuma equation